Main distribution arrangements designed for telephone or switchboard exchanges have been shown in several different embodiments. These arrangements take up a large portion of the overall space allocated for a complete telephone exchange.
It is known that within a modern telephone exchange approximately 80% of the total volume is occupied by line circuit boards and the main distribution arrangement that is connected to them.
It is also a known practice to coordinate telephone exchange-related line circuits on printed board assemblies (called line interface boards); that is, on printed boards with surface-mounted discrete components. These printed board assemblies are then positioned in close connection to the main distribution arrangement.
Further, it is known that additional printed board assemblies and similar arrangements make up the structure for the other functions of a telephone exchange, creating conditions whereby they may interact electrically with the line circuits and their printed board assemblies.
It is also a known practice to build up line interface boards with line interface board magazines and cabinets, which use the same infrastructure as other parts and functions of the telephone exchange; for example, switches and processors.
A Main Distribution Frame (MDF) or an internal switchboard--with which the line circuits can be redistributed internally in the switch--is required in order to connect each line circuit constructed on the line interface board to an arbitrary subscriber.
Conductors from the subscribers' cables are terminated at connectors, arranged in blocks or contact units. Similarly, subscriber-related conductors from the line interface boards are terminated at connectors, arranged in blocks or contact units.
Blocks of this kind are mounted in an independent infrastructure, and ofttimes consist of U-beams, which function as carriers.
The previously disclosed characteristics that are associated with the present invention include diverting heat to, and cooling it at, adjacent cooling flanges--the heat is produced by discrete components mounted on printed boards.
As examples of the background art we refer to the publications EP-A1-0 564 315; EP-A2-0 449 150; U.S. Pat. No. 4,758,924; U.S. Pat. No. 5,237,486; and DE-C2-3 717 009.
Similarly, the following publications relate to the background art:
GB-A-2 132 445
This publication shows and describes a main distribution frame (MDF) for a telephone exchange, including a terminal field (2) for connecting to subscriber conductors; and contact units that plug into a type of line interface board unit that is suitable for the lines that are served. The rack is divided into two sections.
The contact units are related to blocks. Each block is equipped with a back plane that supports the conductors for said block.
Each back plane provides access to the TDM link for the connection equipment.
A number of block sets are shown to include several blocks that are aligned one above the other in a column, where a central column and an inner block provide access to the stretches of cable.
Patent Abstract of Japan, Abstract of JP 59-115692, Pub. Jul. 4, 1984
This publication shows line interface boards that consist of a line circuit module 9 with plug-in type connection terminals 10.
The modules can, independently of one another, be inserted or removed from the frame structure 7.
An additional module 21 can be attached to the module 9 via a plug-in system.
EP-A2-0 349 285
This publication shows another plug-in type of module with several modules that can be inserted or removed from a rack arrangement.
The modules are positioned side by side.
Said module consists of a mother board and several daughter boards with an application of printed circuits. Two edge-related guide bars are affixed to the board.
Further, each module includes several individually-removable printed board assemblies that relate to each daughter board.
The plug-in system of a circuit module, which can be made to interact with a rack arrangement, shows that a module (10), seen in FIG. 1, must be designed as a printed circuit board (12) with a back edge (20), a front edge (18), and upper and lower edges (14, 16). The back edge (20) is equipped with a distribution module (22) that stretches the entire length of the edge (20) and is designed to interact with a corresponding distribution module in the back plane.
The board module shows several parallel guiding tracks that are used to hold four printed board assemblies (34). These relate to the daughter board, and are adapted to interact with the circuit module.
U.S. Pat. No. 5,309,320
This publication shows a component board whose body, which can be cast of a thermally-conductible dielectric material, is cast as a printed circuit board whose design exactly conforms to that of an electronic arrangement.
A metal plate can form part of a converter.
The converter can be applied to a cold plate and a printed circuit board box in order to conduct heat from the electronic components.
A direct casting process may be used.
EP-A2-0 272 521
This publication shows a back plane with a bar (2) for inserting or removing a printed board assembly (4) that has a back plane-related means of connection (3).
In order to divert heat, a front plate (6) is equipped with cooling flanges (7).
In particular, this invention comprises the arrangement for inserting and removing the printed board assembly.
Further, the publication shows that the inside is equipped with a contact organ (3) that interacts with the contact organ of the connection plate(4) inside the cover (5).